Introdouction: Injection of local anesthesia during dental procedures can induce metabolic changes. The purpose of this study was to evaluate the changes in the serum blood glucose levels after the injection of lidocaine with a vasoconstrictor during tooth extraction. Materials and methods: In this clinical trial study, we enrolled 60 patients. We extracted mandibular teeth by using inferior alveolar nerve block. We took a finger blood sample test from each enrolled patient immediately before and 10 min after local anesthesia administration. The anesthetic solution (1.8 mL carpule) contained lidocaine and 1:80,000 epinephrine. It was injected through the inferior alveolar nerve after negative aspiration. Only one carpule was injected into each patient. This study is approved by the ethics committee of the research center of Azad University of Medical Sciences.Results: The mean age of the patients in our study was 39.54 ± 15 years. Thirty-five patients were male, and 25 were female. The serum blood glucose level was 111.6 ± 25.47 mg/dL before local anesthesia and 115.3 ± 24.39 mg/dL after tooth extraction (P = 0.418). Eleven female patients and four male patients had a reduction in the blood glucose levels after injection. There was a significant difference between these groups (P = 0.01).Conclusion: According to our findings and previous reports, using local anesthesia during tooth extraction does not induce hypoglycemia and could increase the serum blood glucose level in individuals.